Field of the Invention
The present invention relates to a radiation image pickup apparatus and a radiation image pickup system which are considered useful for medical diagnosis and an industrial non-destructive testing, a method for controlling the radiation image pickup apparatus, and a program.
Description of the Related Art
A radiation image pickup apparatus includes a pixel array disposed in a two-dimensional matrix form. The pixel array includes pixels which convert a radiant energy (radiant rays) into electric signals. A signal processor outputs digital signals based on the electric signals of the pixels, and a power supply unit supplies voltages to the pixel array and the signal processor. Japanese Patent Application Laid-Open No. 2002-165142 discloses a power-saving configuration in which a power supply unit includes a first power source which supplies a voltage to a pixel array and a second power source which supplies an operating voltage to a signal processor and a controller controls the power supply unit so that the first and second power sources are individually controlled. Furthermore, Japanese Patent Laid-Open No. 2002-165142 discloses a technique of supplying an operating voltage from the second power source to the signal processor after irradiation of a radiant ray to the pixel array is completed and outputting digital signals from the signal processor when a predetermined period of time is elapsed after the signal processor receives the operating voltage from the second power source.
However, when the method disclosed in Japanese Patent Laid-Open No. 2002-165142 is used, although the power saving is attained, artifact may be generated in an image obtained by a radiation image pickup apparatus in accordance with digital signals output from the signal processor. The artifact may be generated when a voltage applied to elements in the signal processor has not reached a desired value even when a predetermined period of time has elapsed after an operating voltage source is supplied to the signal processor. On the other hand, if the predetermined period of time is set long so that a voltage applied to the elements included in the signal processor attains the desired value, a period of time from when the irradiation of a radiant ray is completed to when an image is obtained becomes long.